Enhanced adsorption performance of the graphene oxide with metallic ion impurities by elution

The graphene oxides (GOs) with various content of metallic ions impurities were prepared, and the adsorption performance of the GO before and after elution was evaluated. The prepared GOs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma and atomic force microscopy. The results indicated that the metallic ion impurities hardly affected the interlayer distance, microstructure and thickness of the prepared GOs. The adsorption isotherm and adsorption kinetic results showed that the metallic ions adsorbed on the GO surface had a negative influence on both the adsorption capacity and rate. After eluted by HNO3 or HCl, most of the metallic ions adsorbed on the GO-91 surface were ion-exchanged by the protons of the acid eluents, and the purified GO showed enhanced equilibrium capacities and improved adsorption rate. The elution efficiency of HCl was better than that of HNO3, and the adsorption capacity and rate of the GO eluted by HCl approximately reached to those of the GO prepared from the graphite with high purity. It indicated that HCl could efficiently remove the metallic ions adsorbed on the GO surface. Copyright (C) 2017 John Wiley & Sons, Ltd.